The first recorded impact The first recorded impact crater on the Earth: crater on the Earth:

Carancas, PeruCarancas, Peru

G. Tancredi and several G. Tancredi and several colleagues from Peru colleagues from Peru

and many other countriesand many other countries

Dpto. Astronomía, Fac. Ciencias, Dpto. Astronomía, Fac. Ciencias, Montevideo, UruguayMontevideo, Uruguay

gonzalo@fisica.edu.uygonzalo@fisica.edu.uy

¿What did happen?¿What did happen?

15/9/2007 – ~ 11:45 LT (16:45 UT) a bright fireball was 15/9/2007 – ~ 11:45 LT (16:45 UT) a bright fireball was observed in the sky, leaving behind an smoke trail. observed in the sky, leaving behind an smoke trail. Strong explosions lasting several seconds were heard in Strong explosions lasting several seconds were heard in an area of several tens of km long. An explosion was an area of several tens of km long. An explosion was observed as well as the formation of a thick cloud of dust observed as well as the formation of a thick cloud of dust like a mushroom cloud.like a mushroom cloud.The shock wave produce the vibration of several houses The shock wave produce the vibration of several houses and some animals were knocked down due to the shock and some animals were knocked down due to the shock wave. The roof of a shed was impacted by ejecta.wave. The roof of a shed was impacted by ejecta.In the site where the explosion and the dust cloud was In the site where the explosion and the dust cloud was observed, the local people found a ~15m crater. The observed, the local people found a ~15m crater. The crater was half-fill by underground water. The water was crater was half-fill by underground water. The water was bubbling and noxious fumes were coming out the water.bubbling and noxious fumes were coming out the water.Several pieces of atypical material was collected from Several pieces of atypical material was collected from inside and outside the crater.inside and outside the crater.Several persons got sick.Several persons got sick.

Preliminary considerationsPreliminary considerations

A stony meteorite enter the upper atmosphere at A stony meteorite enter the upper atmosphere at velocities ~12-20 km/s. As a consequence of the friction velocities ~12-20 km/s. As a consequence of the friction with the air molecules, the body heats up and material with the air molecules, the body heats up and material from the surface is vaporized. The hot gas cloud that is from the surface is vaporized. The hot gas cloud that is formed around the body is observed as a fireball formed around the body is observed as a fireball crossing the sky at high speed. The phenomena last just crossing the sky at high speed. The phenomena last just a few seconds. In its passage it leaves behind a smoke a few seconds. In its passage it leaves behind a smoke trail. Due to the supersonic speeds and possible trail. Due to the supersonic speeds and possible fragmentations, the shock wave produces a sonic boom fragmentations, the shock wave produces a sonic boom that last for several seconds.that last for several seconds.Though the body is largely decelerated in the passage Though the body is largely decelerated in the passage through the atmosphere, it retains an important fraction through the atmosphere, it retains an important fraction of its original spped and it impacts the ground producing of its original spped and it impacts the ground producing a crater.a crater.

The soundsThe sounds

The witnessThe witness

Photo of the smoke trailPhoto of the smoke trail

Crater: diameter 14mCrater: diameter 14m

Carancas meteoritesCarancas meteorites

Photo José Ishitsuka

Other meteorites foundOther meteorites found

60 gr

22 gr

20 gr

Chondrite

Achondrite

Iron

Photo 1: Transmitted light optical image. In the center a radiating pyroxene chondrule. Plane polarized light

Photo2: Detail of the radiating pyroxene chondrule. Cross polarized light

Photo3: Olivine rich object characterized by having a barred-olivine texturein the center and a thick olivine rim. Plane polarized light

MINERALOGY COMPOSITIONMINERALOGY COMPOSITION

Piroxene 1 Piroxene 1 40 %40 %OlivineOlivine 20 %20 %FeldespatFeldespat 10 %10 %Piroxene 2Piroxene 2 10 %10 %Opaque minerals accounting for 20 % of the Opaque minerals accounting for 20 % of the mass, they inlcude:mass, they inlcude:KamaciteKamacite 15% 15%TroiliteTroilite 5 %5 %CromiteCromite tracestracesCupper nativeCupper native tracestraces

Analysis from INGEMMET, Peru

Fer

rosi

lite

in O

rtop

iroxe

ne

Fayalite in Olivine

Clasification Clasification (M. E. Varela et al.)(M. E. Varela et al.)

Ordinary Chondrite type H4/5

Crater Aristarco, Moon

Impact Crateres by Impact Crateres by comets and asteroidscomets and asteroids

Meteor Crater Barringer, Arizona1.2 km, 49.000 yr

Crater Double Clearwater, Canada32 6 22kkm, 290 Myr

Crater Manicouagan, Canada100 km, 212 Myr

Tunguska, 1908 (photo taken by Kulik in 1928)

Recent records of impact cratersRecent records of impact craters

YearLocation of the

crater

Diameter of largest crater

Number of craters or

pits

Total mass of found

meteorites

Meteorite type

1998Kunya-Urgench, Turkmenistan

6 m Single 1.1 tons Chondrite H5

1990Sterlitamak, Russia

10 m Single 0.3 tons Iron IIIAB

1976 Jilin, China 4m Multiple 4 tons Chondrite H5

1947Sikhote-Alin, Russia     

27 m Multiple 23 tons Iron IIAB

Jilin, China (1976)Jilin, China (1976)

Penetration hole

Sterlitamak, Rusia (1990)Sterlitamak, Rusia (1990)

Sikhote-Alin (1947)Sikhote-Alin (1947)

Sikhote-Alin strewn fieldSikhote-Alin strewn field

Carancas craterCarancas crater

Impact regimesImpact regimes

The size of the projectileThe size of the projectile

Impact Energy on the surfaceImpact Energy on the surface

Home experimentHome experiment

Ejecta at 300m in SW direction

The ejected materialThe ejected material

Big size ejecta at 100m in NE directionLocation of ejecta in NE direction

Roof of a shed at ~75m from the craterRoof of a shed at ~75m from the crater impacted by ejectaimpacted by ejecta

Distribution of ejected material Distribution of ejected material (Rosales et al. 2008)(Rosales et al. 2008)

Speed of the ejected materialSpeed of the ejected material

Shock Metamorphism of the target Shock Metamorphism of the target material and the projectilematerial and the projectile

French (1998)

Meteorites fragments embedded in the Meteorites fragments embedded in the soil soil (Harris et al. 2008)(Harris et al. 2008)

Quartz grains with shock Quartz grains with shock metamorphism due to impact metamorphism due to impact

(Harris et al. 2008)(Harris et al. 2008)

Conclusions about the Conclusions about the petrology studiespetrology studies

The meteoritic mass penetrated deeply at a high The meteoritic mass penetrated deeply at a high speed while coupling its energy to the subsurface speed while coupling its energy to the subsurface to produce surface spalls, inverted rim ejecta, to produce surface spalls, inverted rim ejecta, injection of meteoritic debris between contrasting injection of meteoritic debris between contrasting soil horizons, long crater rays, and excavation of soil horizons, long crater rays, and excavation of horizons not exposed on the surface.horizons not exposed on the surface.

Regarding the level of shock metamorphism of the Regarding the level of shock metamorphism of the target material, we estimate target material, we estimate

Pressures > 10GPaPressures > 10GPa

The impact velocity was > 3 km/s and possibly on The impact velocity was > 3 km/s and possibly on the order of 4 to 6 km/sthe order of 4 to 6 km/s

Infrasound and Seismic detectionsInfrasound and Seismic detections

Infrasound detection Infrasound detection (Brown et al. 2008)(Brown et al. 2008)

Infrasound station I08BO in La Paz, Bolivia (80 km from crater)

Infrasound station I41PY in Asuncíon, Paraguay (1617 km from crater)

Seismic detections Seismic detections (LePichon et al. 2008)(LePichon et al. 2008)

First seismic detection of an extraterrestrial impact on Earth

Estimate of the trajectory through the Estimate of the trajectory through the atmosphereatmosphere

Facts to take into account• Backazimuth from infrasound station I08BO

determined from the array of detectors• Arrival time in the seismic waves and of the

air shoch waves at the seismic and infrasound stations

• Witnesses that saw the fireball• Distribution of ejected material,

concentration in the SW direction

Orbital elements of the meteoroidOrbital elements of the meteoroid

Impact time: Impact time: 16h 40m 14s UT16h 40m 14s UT

Radiant: Radiant: Az ~ 80-110°Az ~ 80-110°

Alt ~ 45-60°Alt ~ 45-60°

Pre-atmospheric velocity: 12-18 km/sPre-atmospheric velocity: 12-18 km/s

Location of the radiants in equatorial Location of the radiants in equatorial coordinates relative to the Sun coordinates relative to the Sun (Tancredi et al. 2008)(Tancredi et al. 2008)

Radiants of NEAs

Sun

Anti-Sun

Elements compared with NEAsElements compared with NEAs

Direct EntryModelingResults:Example(D. Revelle et al.)

Why is this event so relevant?Why is this event so relevant?

1.1. Fresh fall with many witnessesFresh fall with many witnesses

2.2. An impact crater was formed An impact crater was formed

3.3. Impact at high latitude, less deceleration in the Impact at high latitude, less deceleration in the atmosphereatmosphere

4.4. Ordinary chondrite meteorite that survives the Ordinary chondrite meteorite that survives the passage through the atmospherepassage through the atmosphere

5.5. Several records of infrasound and seismic dataSeveral records of infrasound and seismic data

6.6. Collection of material from the ground and the Collection of material from the ground and the meteorite with shock metamorphismmeteorite with shock metamorphism

Preliminary ConclusionsPreliminary Conclusions

Initial Mass of the meteoroid: 7 to 12 tonInitial Mass of the meteoroid: 7 to 12 ton– Initial Diameter: 1.6 – 2 mInitial Diameter: 1.6 – 2 m

Initial Velocity: 12 – 17 km/sInitial Velocity: 12 – 17 km/s– Initial Energy: 0.12 – 0.41 kT TNTInitial Energy: 0.12 – 0.41 kT TNT

Trayectory with Az: 80° - 110°, Alt: 45° - 60°Trayectory with Az: 80° - 110°, Alt: 45° - 60°

Impact Velocity on the ground: ~> 3 km/s Impact Velocity on the ground: ~> 3 km/s

Mass of the impactor: 1 – 2.5 tonMass of the impactor: 1 – 2.5 ton– Diameter: 0.8–1.1m ; Impact Energy: ~2–4 tons TNTDiameter: 0.8–1.1m ; Impact Energy: ~2–4 tons TNT

There is no indications of large remnants of the There is no indications of large remnants of the meteorite inside the crater meteorite inside the crater (see Ishitsuka presentation)(see Ishitsuka presentation)

What else do we want to know?What else do we want to know?

Confirm the pressure and temperatures reached Confirm the pressure and temperatures reached at the time of impact and the velocity of the at the time of impact and the velocity of the impactorimpactorWhat does happen with the original meteorite? What does happen with the original meteorite? Was it fragmented and totally dispersed during Was it fragmented and totally dispersed during the impact?the impact?How was it possible that a chondrite meteorite of How was it possible that a chondrite meteorite of just a few meters in size could get through the just a few meters in size could get through the atmosphere without being completely disrupted?atmosphere without being completely disrupted?

In which conditions could this event In which conditions could this event happen again?happen again?

Research TeamResearch TeamG. TancrediG. Tancredi - - Dpto. Astronomía, Fac. Dpto. Astronomía, Fac. Ciencias, Iguá 4225, 11400 Montevideo, Ciencias, Iguá 4225, 11400 Montevideo, Uruguay, gonzalo@fisica.edu.uyUruguay, gonzalo@fisica.edu.uyJ. Ishitsuka, D. Rosales, E. VidalJ. Ishitsuka, D. Rosales, E. Vidal - - Instituto Geofísico del Perú, Lima, PerúInstituto Geofísico del Perú, Lima, PerúP. Schultz, R. S. HarrisP. Schultz, R. S. Harris - - Dept. Geological Sciences, Brown University, Rhode Dept. Geological Sciences, Brown University, Rhode Island, USA.Island, USA.P. BrownP. Brown - Dept. of Physics and Astronomy, University of Western Ontario, - Dept. of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 CanadaLondon, ON N6A 3K7 CanadaD. RevelleD. Revelle - EES-2, Atmospheric, Climate and Environmental Dynamics Group - EES-2, Atmospheric, Climate and Environmental Dynamics Group – Meteorological Modeling Team, Los Alamos National Laboratory, P.O. Box – Meteorological Modeling Team, Los Alamos National Laboratory, P.O. Box 1663, MS D401, Los Alamos, NM 87545 USA1663, MS D401, Los Alamos, NM 87545 USAK. Antier, A. Le PichonK. Antier, A. Le Pichon - - Commissariat à l’Energie Atomique, Centre DAM - Ile Commissariat à l’Energie Atomique, Centre DAM - Ile de France, Département Analyse Surveillance Environnement, Bruyères-le-de France, Département Analyse Surveillance Environnement, Bruyères-le-Châtel, 91297 Arpajon Cedex, France.Châtel, 91297 Arpajon Cedex, France.S. BenaventeS. Benavente - - Universidad Nacional del Altiplano, Puno, PerúUniversidad Nacional del Altiplano, Puno, PerúP. Miranda, G. PereiraP. Miranda, G. Pereira - - Planetario Max Schreier, Universidad Mayor de San Planetario Max Schreier, Universidad Mayor de San Andrés, La Paz, BoliviaAndrés, La Paz, BoliviaM. E. VarelaM. E. Varela - - Complejo Astronómico El Leoncito – CASLEO, San Juan, Complejo Astronómico El Leoncito – CASLEO, San Juan, ArgentinaArgentinaF. BrandstätterF. Brandstätter - - Naturhistorisches Museum, Vienna, AustriaNaturhistorisches Museum, Vienna, Austria L. SánchezL. Sánchez - - Inst. Ciencias de la Tierra, Fac. Ciencias, Iguá 4225, 11400 Inst. Ciencias de la Tierra, Fac. Ciencias, Iguá 4225, 11400 Montevideo, UruguayMontevideo, Uruguay